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    SubjectRe: [RFC/RFT PATCH v3] sched: automated per tty task groups
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    On Fri, 2010-11-19 at 01:07 +0100, Samuel Thibault wrote:
    >
    >
    > Also note that having a hierarchical process structure should permit to
    > make things globally more efficient: avoid putting e.g. your cpp, cc1,
    > and asm processes at three corners of your 4-socket NUMA machine :)

    We have the hierarchy mandated by POSIX to track parents, childs,
    sessions and all that stuff, its just not the data structure used for
    scheduling.

    And no, using that to load-balance between CPUs doesn't necessarily help
    with the NUMA case, load-balancing is an impossible job (equivalent to
    page-replacement -- you simply don't know the future), applications
    simply do wildly weird stuff.

    From a process hierarchy there's absolutely no difference between a
    cc1/cpp/asm and some MPI jobs, both can be parent-child relations with
    pipes between, some just run short and have data affinity, others run
    long and don't have any.




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